I live in South Florida and have lived through multiple hurricanes and their aftermath including going a month without electricity. That means I own several coolers. My best is a roto-molded, commercial grade marine cooler by IceyTek which is the company that became Yeti. It will hold ice for 8 to 10 days and stay cold even after the ice melts for another couple of days. If you need to keep stuff cold for more than a couple of days, you have to go with a marine cooler.
I have an ancient green Thermos that dates from the 1960's. It is slowly rusting away. I should paint the thing, I suppose. I used it last week. I am down to one soft lunch box sized unit and a small Igloo cooler. I take the Igloo with me regularly. I keep some Coleman freeze blocks instead of ice generally. Best wishes. G